1. Field of the Invention
The present invention is directed to a method of preparing a diffusion transfer image-receiving material and, more paticularly, it is directed to a method of preparing a diffusion transfer image-receiving material by hydrolyzing the surface portion of an alkali non-diffusible polymer sheet to render the surface portion alkali diffusible and absorbing into the sheet silver precipitating nuclei (hereinafter the nuclei are called "diffusion transfer nuclei") from a solvent such as water, a ketone, and an alcohol containing the diffusion transfer nuclei.
2. Description of the Prior Art
A diffusion transfer image-receiving material has been generally prepared by a method in which diffusion transfer nuclei are dispersed in a hydrophilic polymer or an alkali diffusible polymer and applying the dispersion onto a support, or a method in which diffusion transfer nuclei are dispersed in an oleophilic high molecular weight material, the dispersion is dissolved mixed in an organic solvent, the solution is applied to a support, and then the oleophilic high molecular weight material thus coated is hydrolyzed to render the coated layer of the material alkali diffusible (see, e.g., Japanese Pat. No. 32,754/1969).
In the former method, as the hydrophilic high molecular weight material gelatin, polyacrylic acid, a maleic anhydridemethyl methacrylate copolymer, a vinyl derivative (such as polyvinyl alcohol, polyvinyl pyrrolidone, etc.), a cellulose derivative (such as carboxymethyl cellulose, hydroxyethyl cellulose, etc.), the metal salts of these materials, and the alginates of these materials, are used.
However, the image-receiving material prepared by the method has the disadvantages that in the type of diffusion transfer material having a silver halide emulsion layer coated on the image-receiving layer, the silver halide emulsion layer tends to be difficult to separate from the surface of the image-receiving layer, which makes it necessary to provide a specific separating layer between both of the layers; it takes a long period of time to dry the image-receiving layer after washing the diffusion transferred image-receiving layer with water; the surface of the image-receiving layer retains a sticky feeling even after drying; and also the silver image obtained by the diffusion transfer process is weak mechanically or chemically.
In the latter method a material to be used as the diffusion transfer nuclei is absorbed in an oleophilic polymer using vacuum evaporation, the oleophilic polymer containing the material is dissolved in a solvent which does not dissolve the diffusion transfer nuclei, and after forming a layer of the oleophilic polymer from the solution, the polymer layer containing the diffusion transfer nuclei is chemically treated. Thus, the diffusion transfer nuclei are dispersed throughout the entire layer of the alkali diffusible material.
However, this method is also accompanied by the following difficulies. First, although the techniques for vacuum evaporation are considerably developed at present, it is still technically difficult to obtain a constant condition for producing the diffusion transfer nuclei in the case of preparing a large amount of the nuclei for such a purpose as in this method. Also, as described above, in this method the surface portion of the layer of an alkali non-diffusible polymer prepared by incorporating a material used as the diffusion transfer nuclei in the alkali non-diffusible polymer by vacuum evaporation, dissolving the alkali non-diffusible polymer containing the nuclei in an oganic solvent, and applying the solution to a support is provided with an alkali diffusible property by hydrolysis. In this case, however, the diffusion transfer nuclei present in only the alkali diffusible surface portion of the layer are effectively utilized in the diffusion transfer process but the diffusion transfer nuclei present in other portions of the layer, that is, in the alkali non-diffusible portions of the layer are present for no purpose. Furthermore, by hydrolyzing the alkali non-diffusible polymer layer containing the diffusion transfer nuclei, the nuclei contained in the layer are decreased in activity as the silver precipitating agent at diffusion transfer.
An object of this invention is, therefore, to provide a diffusion transfer image-receptive material having excellent properties unaccompanied by the above-described difficulties.